I was thinking that since ys engines run on pressureized tanks that my 120 should run fine inverted, am I right? Im mounting it on a Sig Raskall 110 and the only way to mount it is inverted.Should it work?

Inverted is no different than upright or sideways. No worries.

Ok guys so I got my 120 mounted on the Raskall inverted, its dripping fuel out of the carb, its not a steady run but enough to soak the glow ignighter fairly well. When I fire it up it really doesnt want to run properly, all it wants to do is go high throttle and then down and back to high throttle again, and its doing that repedilly up and down and up and down, and when I try to remove the glow ignighter it will die.I was haveing an issue with it back fireing so I went ahead and changed the diafram out with a new one and this is the first time its been ran since changeing it out and mounting it inverted. Its my first YS engine and dont know much about it other than what ive read here. Please any help would be greatlly apreciated.

Scott

It's not because it's inverted. Could be some grunge in the regulator or you need a new plunger and maybe a diaphragm.

Ok so say there could be some grung? what can I do to cleane it out? can I use carb cleaner? or some other type of spray cleaner on it to blow out the trash? Ive allso thought about packageing it up and sending it in to YS there in Vegas and have them go thrue it, would that be a wise choice? Whats the cost of doing that?

As far as cleaning it out, I just disassemble it and squirt it out with fuel.
If that doesn't stop the leaking when the throttle is at idle with pressurized tank then
replacing the plunger and diaphragm is an easy fix and routine maintenance.

If you're dripping fuel the regulator is not closing. Pull it apart and flush it with raw fuel, while you have it apart a new diaphram, plunger and spring would be good ideas. Plungers rarely need replaced but since you have it apart why not.

Thanks for the info guys, ok so on the diaphram does it have to be seated, or does it just lay flat on the reagulator body? I took it all apart and cleaned everything and put it all back together, I dont have all new parts to replace them with so I have to reuse what I have. I tried to start it but its not fireing now, it wont start. But its not leaking fuel no more. Ive got a OS #7 plug it it and useing Byrons 20\20 fuel (the purple stuff)

SCOTT42,

                     Although some folks use the OS #7 glow plug in their four strokes OS states that it is primarily a two stroke plug.

I would recommend you use the YS four stroke plug, also the OS type F or any of the Merlin four stroke plugs.
(Merlin recommends the #2009 plug for inverted applications)

http://www.merlinglowplugs.com/Aircraft.html

YS plugs at...

http://www.centralhobbies.com/

Happy flying, Oscar

You probably have the regulator to lean. Start with the regulator screw set flush. Watch the short fuel tube between the regulator and the carb while turning over the engine. You should see some fuel movement in that tube. If not, the regulator is probably set too lean. Back out the set screw an 1/8 turn at a time until you see fuel flowing there. Sometimes priming the engine will help get the regulator working. I would try that.

Thanks guys, I posted the wrong plug on my last post, not sure where I came up with the #7? it is the os type F thats in it. Ok so i have since double checked myself to make sure I put it back together the right way and tried to start it again and it seems to be leaking again, but I cant see fuel moveing in that little line you were talking about. Ive put it away for a few days untill I can just buy all new stuff and just rebuild it correctlly with new stuff. Thanks guys for your help, i will check back after I get all the stuff needed.

Scott

Ok, so I have bought all the stuff to rebuild the regulator 100%, since doing that it has made a BIG differance now, it will actully run now. I ran a tank thru it the other day at low, med, and high throttle and no troulbes of sputtering, or leaning out onec i got the regulator set. So now my big question is what should i be looking for on RPM range? High and low? Ive got an 16x8 wood zinger prop on it now, mwhat kind of rpms should I be looking for? Thanks guys.

SCOTT42,

This a really good tutorial on tuning the YS 120 and just about all the other YS engines

http://www.geistware.com/rcmodeling/index.htm

Just scroll down to the YS section and click on YS Engines, this gives best RPMs and idle speed.
There are also suggestions on prop selection.

Remember that you want to tune for the RPM that the engine performs "on the cam" where you are getting the best
efficiency and not the maximum RPM.
Usually this is about 8000 RPM, so you want to prop the engine so that it turns at this speed running
a bit on the rich setting, you should set the idle below 2000 RPM.


Good luck


Happy flying, Oscar